/*
 * Copyright (C) 2009 M. Hautle.
 * 
 * This file is part of TrackedBean.
 * 
 * TrackedBean is free software: you can redistribute it and/or modify it under the terms of the GNU Lesser General Public License as published by the Free
 * Software Foundation, either version 3 of the License, or (at your option) any later version.
 * 
 * TrackedBean is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
 * A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more details.
 * 
 * You should have received a copy of the GNU Lesser General Public License along with TrackedBean. If not, see <http://www.gnu.org/licenses/>.
 */
package ch.trackedbean.validator.engine;

import java.util.*;
import java.util.regex.*;
import ch.trackedbean.validator.*;
import ch.trackedbean.validator.defaultValidators.*;

/**
 * Interpolator for {@link AbstractValidator}s messages.<br>
 * If you want to override the default messages then create your own resource bundle in <code>META-INF/services</code> using the
 * <code>ch.trackedbean.validator.messages</code> as base name.
 * 
 * @author M. Hautle
 */
public class DefaultInterpolator implements IInterpolator {
	/** The location of the default message properties file. */
	private static final String DEFAULT_PROPERTIES = "ch.trackedbean.validator.engine.resource.messages";

	/** The location of the user message properties file. */
	private static final String USER_PROPERTIES = "META-INF/services/ch.trackedbean.validator.messages";

	/** An empty resource bundle. */
	private static final ResourceBundle EMPTY_BUNDLE = new ResourceBundle() {
		@Override
		public Enumeration<String> getKeys() {
			return null;
		}

		@Override
		protected Object handleGetObject(String key) {
			return null;
		}
	};

	/** The resource bundle for the default messages. */
	private final ResourceBundle defaultMsg;

	/** The resource bundle for the user messages. */
	private final ResourceBundle userMsg;

	/** Pattern to use for detetcting the place holders. */
	private final Pattern placeHolder = Pattern.compile("\\$\\{(\\d+?)\\}");

	/**
	 * Default constructor.
	 */
	public DefaultInterpolator() {
		defaultMsg = ResourceBundle.getBundle(DEFAULT_PROPERTIES);
		ResourceBundle user = EMPTY_BUNDLE;
		try {
			user = ResourceBundle.getBundle(USER_PROPERTIES);
		} catch (MissingResourceException e) {
		}
		userMsg = user;
	}

	/**
	 * Default constructor.
	 * 
	 * @param resourceFile The resource bundle base file name
	 */
	public DefaultInterpolator(String resourceFile) {
		defaultMsg = ResourceBundle.getBundle(DEFAULT_PROPERTIES);
		userMsg = ResourceBundle.getBundle(resourceFile);
	}

	/**
	 * {@inheritDoc}
	 */
	public String getMessage(String key) {
		try {
			return userMsg.getString(key);
		} catch (MissingResourceException e) {
			// do a lookup in the default message bundle if the user lookup failed
			return defaultMsg.getString(key);
		}
	}

	/**
	 * {@inheritDoc}
	 */
	public String getMessage(String key, Object[] values) {
		final String msg = getMessage(key);
		final Matcher m = placeHolder.matcher(msg);
		final StringBuilder str = new StringBuilder();
		int start = 0;
		while (m.find()) {
			str.append(msg.substring(start, m.start()));
			str.append(values[Integer.parseInt(m.group(1))]);
			start = m.end();
		}
		str.append(msg.substring(start));
		return str.toString();
	}
}
